CONTROL OF BODY

TEMPERATURE AND

WATER BALANCE

THERMOREGULATION

- The process by which animals maintain an

internal temperature within a tolerable range.

- Each species of animal has an optimal

temperature range.

- helps keep body temperature within that

range, enabling cells to function effectively even

when the external temperature fluctuates.

Two modes of thermoregulation

Endotherms – are warmed mostly by

heat generated by their own metabolism.

Ectotherms - they gain most of their

heat by absorbing it from external sources.

Heat is gained or lost in four ways

Thermoregulation involves adaptations that

balance heat gain and loss

Five categories of adaptations:

1. Metabolic Heat Production- cold weather,

hormonal changes tend to boost the metabolic

rate of birds and mammals, increasing their

heat production.

2. Insulation- an adaptation that reduces the

flow of heat between and animal and its

environment.

3. Circulatory Adaptations- Heat loss

can be altered by changing the amount of

blood flowing to the skin.

.

4. Evaporative Cooling-

Many animals live in

places where

thermoregulation requires

cooling as well as warming

5. Behavioral

Responses- Both

endotherms and

ectotherms control body

temperature through

behavioral responses

OSMOREGULATION AND EXCRETION

Osmoregulation - is the homeostaticcontrol of the uptake and loss of water andsolutes, dissolved substances such as salt(NaCl) and other ions.

osmoconformers, such animals do notundergo a net gain or loss of water.

Osmoregulators- must actively regulatewater movement

The urinary system plays several major roles in homeostasis

Urinary system

- plays a central role inhomeostasis, forming and excreting urinewhile regulating the amount of water andsolutes in body fluids.

- In humans, the main processingcenters of the urinary system are the twokidneys.

Every day, our kidneys extract about

180 L of fluid, called filtrate,

consisting of water, urea, and a

number of valuable solutes, including

glucose, amino acids, ions, and

vitamins.

Urine leaves each

kidney through a

duct called a

ureter.

Both ureters drain

into the urinary

bladder.

Urine is expelled

from the bladder

through a tube

called the urethra

Two main

regions:renal cortex (outer)

renal medulla (inner)

Each kidney contains

about a million tiny

functional units called

nephrons.

Bowman’s capsule,is a cup-shaped

swelling, the receiving

end of the nephron

Bowman’s

capsule envelops

a ball of

capillaries called

the glomerulus

(plural, glomeruli).

The tubule has three

sections:

1. the proximal tubule (in

the cortex)

2. the loop of Henle, a

hairpin loop with a

capillary network that

carries filtrate toward—

and in some cases into—

the medulla and then

back toward the cortex

3. the distal tubule

(called distal because it is

the most distant from

Bowman’s capsule).

PROCESSES OF URINARY SYSTEM

Filtration

Reabsorption

Secretion

Excretion

Hormones regulate the Urinary

System

Antidiuretic hormone (ADH) – signals

the nephrons in your kidneys to reabsorb

more water from the filtrate.

- This reabsorption increases the

amount of water returning to your blood

(where it is needed) and decreases the

amount of water excreted (resulting in

concentrated urine).

KIDNEY DIALYSIS CAN BE LIFESAVING

More than 60% of all cases of kidney

disease are caused by hypertension and

diabetes, but the prolonged use of pain

relievers (even common, over-the-counter

ones), alcohol, and other drugs are also

possible causes.

In dialysis, blood is filtered by a machine,

which mimics the action of a nephron.

Dialysis treatment is life sustaining for

people with kidney failure, but it is costly,

takes a lot of time (about 4–6 hours three

time a week), and must be continued for

life—or until the patient is able to undergo

kidney transplantation.

In some cases, a kidney from a living

compatible donor (usually a close relative)

or a deceased organ donor can be

transplanted into a person with kidney

failure.

KIDNEY DIALYSIS CAN BE LIFESAVING